title: TREK-1 currents in smooth muscle cells from pregnant human myometrium.
abstract: The mechanisms governing maintenance of quiescence during pregnancy remain largely unknown. The current study characterizes a stretch-activated, tetraethylammonium-insensitive K(+) current in smooth muscle cells isolated from pregnant human myometrium. This study hypothesizes that these K(+) currents can be attributed to TREK-1 and that upregulation of this channel during pregnancy assists with the maintenance of a negative cell membrane potential, conceivably contributing to uterine quiescence until full term. The results of this study demonstrate that, in pregnant human myometrial cells, outward currents at 80 mV increased from 4.8 ± 1.5 to 19.4 ± 7.5 pA/pF and from 3.0 ± 0.8 to 11.8 ± 2.7 pA/pF with application of arachidonic acid (AA) and NaHCO3, respectively, causing intracellular acidification. Similarly, outward currents were inhibited following application of 10 μM fluphenazine by 51.2 ± 9.8% after activation by AA and by 73.9 ± 4.2% after activation by NaHCO3. In human embryonic kidney (HEK-293) cells stably expressing TREK-1, outward currents at 80 mV increased from 91.0 ± 23.8 to 247.5 ± 73.3 pA/pF and from 34.8 ± 8.9 to 218.6 ± 45.0 pA/pF with application of AA and NaHCO3, respectively. Correspondingly, outward currents were inhibited 89.5 ± 2.3% by 10 μM fluphenazine following activation by AA and by 91.6 ± 3.4% following activation by NaHCO3. Moreover, currents in human myometrial cells were activated by stretch and were reduced by transfection with small interfering RNA or extracellular acidification. Understanding gestational regulation of expression and gating of TREK-1 channels could be important in determining appropriate maintenance of uterine quiescence during pregnancy.
authors.affiliation: Department of Pharmacology, Center for Molecular Medicine, University of Nevada School of Medicine, Reno, Nevada.
authors.forename: Nathanael S
authors.initials: NS
authors.lastname: Heyman
authors.forename: Chad L
authors.initials: CL
authors.lastname: Cowles
authors.forename: Scott D
authors.initials: SD
authors.lastname: Barnett
authors.forename: Yi-Ying
authors.initials: YY
authors.lastname: Wu
authors.forename: Charles
authors.initials: C
authors.lastname: Cullison
authors.forename: Cherie A
authors.initials: CA
authors.lastname: Singer
authors.forename: Normand
authors.initials: N
authors.lastname: Leblanc
authors.forename: Iain L O
authors.initials: IL
authors.lastname: Buxton
mesh_terms: D000328:Adult; D002460:Cell Line; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D008564:Membrane Potentials / Q000502:physiology; D032342:Muscle Cells / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism*; D009215:Myometrium / Q000166:cytology / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism; D024683:Potassium Channels, Tandem Pore Domain / Q000235:genetics / Q000378:metabolism*; D011247:Pregnancy; D019789:Tetraethylammonium / Q000378:metabolism; D015854:Up-Regulation; D055815:Young Adult
chemical_list: D015221:Potassium Channels; D024683:Potassium Channels, Tandem Pore Domain; C103742:potassium channel protein TREK-1; D019789:Tetraethylammonium; D011188:Potassium
keywords: TREK-1; human; pregnancy myometrium; smooth muscle; stretch-activated potassium channels; uterus